This practical introduction to OpenLDAP for Application Developers emphasizes how to get things done, going into Lightweight Directory Access Protocol (LDAP) theory only to answer practical questions. It demystifies OpenLDAP, providing a solid understanding of how to use its directory and covering building directory services, integrating directory services, and developing directory-enabled PHP or Python applications. Readers need only basic Linux system administration experience, not LDAP experience. Open-source OpenLDAP directory server is included in all major Linux distributions; many open-source and proprietary applications can use OpenLDAP's services. Client applications use LDAP to connect to OpenLDAP, search the directory, and (if authorized) modify and manipulate records. Most often used to provide network-based authentication services for users, LDAP servers have many other uses: address book, DNS database, organizational tool, even network object store for applications.